My pup is 4 months old. I have started socialization the second week I got her. She is graduating from the Puppy Class next week. I am taking her with me anywhere I go...gas station, friends, parks, etc. Make sure that your pup is not scared of different sounds like vacuum, dropping pans, cars. If see that the dog is scared DO NOT comfort him/her and let her/him figure out the situation by herself. The dog has to understand that the sound is not going to hurt.
We just got back from CT. We drove for 7 hours each way. My pup slept the whole way. We took her to the nursing home to visit out grandpa for the first time. Oh, boy, was I proud of my dog. She was so polite to everyone. She was just sitting for petting and not moving at all (she is only 4 month!). Everybody was in love with her.
I think that well socialized Great Pyrenees dogs make wonderfull therapy dogs. Good luck!